Tokyo Electric Power Co. said Tuesday it has won backing from two municipal governments to apply for a safety assessment of its idled nuclear reactors in Niigata Prefecture.

But Tepco has not yet gained approval from Niigata Gov. Hirohiko Izumida and it remains uncertain when the utility will be able to apply for the assessment, which is a necessary step in restarting the reactors at the Kashiwazaki-Kariwa plant.

The facility is the world's largest nuclear power station. It is in the city of Kashiwazaki and the village of Kariwa.

Kashiwazaki Mayor Hiroshi Aida indicated his approval Tuesday for the assessment, telling a news conference that whether to file applications is "up to the plant operator."

Kariwa Mayor Hiroo Shinada has already expressed its intention to give Tepco the go-ahead.

But Gov. Izumida has been reluctant to allow the utility to apply for the safety checks, citing insufficient investigation into the March 2011 nuclear crisis at the Fukushima No. 1 complex and other reasons.

"I want to meet the governor" for another round of talks, following discussions in July, before applying for the assessment, Tepco President Naomi Hirose told reporters after informing the head of the Natural Resources and Energy Agency of the latest development.

Tepco wants to reactivate its reactors at the Kashiwazaki-Kariwa plant to cut fuel costs for thermal power generation to make up for the halt of its other nuclear power plants.

To resume operation of offline reactors, utilities have to seek confirmation from the Nuclear Regulation Authority regarding whether their facilities satisfy new safety requirements introduced in July.

Other utilities have already applied for the inspection of some of their reactors, but Tepco's application would be more controversial because it is the operator of the crippled Fukushima No. 1 complex.